DECISION TREE APPROACHES TO VOLTAGE SECURITY ASSESSMENT

A decision tree methodology is proposed to tackle voltage security con cerns under two distinct facets, namely preventive-wise and emergency- wise. Decision tree methodology in general consists of inferring infor mation from a 'learning set of states', and of compressing while hiera rchically organising this information in a tree fashion, in terms of s alient parameters automatically selected by the method at its nodes. S ubsequently, the tree may readily assess any already known or new stat e. For preventive voltage stability purposes, trees are built for a gi ven contingency and the system robustness is assessed in terms of prec ontingency parameters. For emergency control purposes, on the other ha nd, each tree is built for a set of contingencies and the system robus tness is assessed in terms of parameters observed just after a conting ency occurrence. The proposed approaches are illustrated by means of t wo simulation studies: one carried out on the Brittany region of the E HV French system and the other on an academic type example. These stud ies explore feasibility aspects, highlight interesting features and su ggest that the proposed approaches have indeed potential for real worl d applications.